Basic Study on Swimming of Small Aquatic Creatures

Abstract

This paper is concerned with the swimming characteristics of small aquatic creatures. The swimming behavior of small aquatic creatures was analyzed by a digital high speed video camera system. The test aquatic creatures were zooplankton and opossum shrimp. Both free swimming and tethered swimming of these aquatic creatures were analyzed. It was found that the average thrust force of aquatic creatures arises from the drag difference between the power stroke and the recovery stroke in beating movement of their swimming legs. Two swimming modes of these aquatic creatures were found out, that is, cruise swimming and sudden swimming were observed. In sudden swimming of the opossum shrimp, thrust force was generated by the water jet. The swimming mechanisms of two kinds of small aquatic creatures were revealed experimentally.